Autism Spectrum Disorders (ASDs) are complex lifelong neurodevelopmental and behavioral disorders manifesting in infancy or early childhood, characterized by impairments in social interaction and communication, and by repetitive, stereotyped behavior. Although the causes of ASD are unknown, the evidence suggests that the origins are likely the result of gene- environment interaction occurring in utero or very early in infancy. The long term goal of this project is to expand our capacity for conducting large scale population-based ASD studies in Jamaica. During the past 2-3 years, with funding from NICHD/FIC (R21 HD057808; PI: Rahbar) our research team at the University of Texas Health Science Center at Houston (UTHealth) has collaborated with Dr. Maureen Samms-Vaughan and her colleagues at the University of the West Indies (UWI) in Jamaica to investigate the role of the glutathione-S-transferase (GST) genes and five heavy metals (lead, mercury, arsenic, cadmium, manganese) in relation to ASD. In the proposed project, we will assess the levels of polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides in the cord-blood isolated from 144 newborns enrolled in the 2011 Jamaican birth cohort to test the hypothesis that children in Jamaica are exposed in utero to these chemicals and identify factors associated with such exposures. In addition, we will conduct an age- and sex-matched case-control study (240 matched pairs) to investigate whether environmental exposures to PCBs and OC pesticides play a role in ASD. Furthermore, we will assess the role of select polymorphisms in GST genes (GSTM1, GSTT1, GSTP1), and their potential interactions with these OCs in relation to ASD. For both cases and controls we will administer a questionnaire to assess the demographic and socioeconomic position, occupation, smoking and drinking status of the parents. In addition, information about family history of developmental disorders, family size, birth order of the index child and whether the child is taking any medications will be collected. Moreover, a dietary questionnaire aimed at capturing possible exposure to environmental contaminants such as PCBs and OC pesticides will be administered. At the end of interview, 1-2 mLs of saliva and about 4-5 mLs of serum will be collected from the case and control children. The DNA isolation and analysis of polymorphisms will be conducted at the Center for Human Genetics at UT School of Public Health. Serum samples will be analyzed for 92 of the 209 PCBs congeners and 18 OC pesticides using capillary column gas chromatography by a CDC-certified lab at the Division of Chemistry and Toxicology at Michigan Department of Community Health in Lansing, Michigan.